I would need help to make a simple custom dimension with 3 custom biomes.

I really don't get how to do what I would like.


I just would like to make a custom dimension named "pestifera''.
Pestifera has to contain 3 custom biomes (very similar to those in the overworld).


    

  1. "pestiferaforet" : a vanilla forest biome
    2. 

  2. "pestiferaneige" : a vanilla snowy plain biome
    3. 

  3. "champipestifera" : a muschroom plain biome (based on the vanilla muschroom island biome)
    4. 



With my current settings I juste have snowy places and plains/forests, but the muschroom biome even if recognized by the game, doesn't appear.


Please help me 🥺
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